原因不明矮小症致病基因研究(附77例报告)

Genetic studies of 77 cases of short stature with unknown etiology

目的应用靶向捕获二代测序技术检测原因不明矮小症致病基因,并分析其与临床表型的相关性。方法收集2007年至2015年在上海交通大学医学院附属瑞金医院儿内科就诊的临床诊断为原因不明矮小症77例患儿的临床资料。制备包括与生长相关的187个基因编码区序列的基因panel,对77例患儿进行二代测序,根据美国医学遗传学与基因组学学会(ACMG)指南评判变异位点,筛选出致病基因,并通过Sanger测序验证,分析患儿基因型和临床表型相关性。结果检测到5例存在致病性变异;1例存在可能致病性变异;1例变异意义不明确。这7种变异均为杂合。1例ACAN基因存在致病性变异p.D2407fs,表现为矮小及骨龄偏大;3例发现PTPN11基因存在已知致病性变异,分别为p.A72G、p.I282V和p.P491S,确诊为Noonan综合征;1例COL2A1基因存在已知致病性变异p.R904C,确诊为Stickler综合征;1例COMP基因存在可能致病性变异p.D401N,可造成多发性骨骺发育不良;1例为家族性矮小患儿,发现GHSR基因新发杂合变异p.S289Y,其骨龄发育落后,基因型与临床表型一致,目前评判意义不明确。结论发现ACAN基因杂合缺陷与骨龄发育超前的特发性矮小相关。COMP基因p.D401N变异,可能与多发性骨骺发育不良有关。GHSR基因新发杂合变异p.S289Y,可能导致矮小,须进一步功能实验验证。

Objective To detect pathogenic genes of short stature with unknown etiology by a targeted next generation sequencing panel to analyze the correlation between genotypes and clinical phenotypes. Methods A total of 77 children diagnosed with unexplained short stature were enrolled for the study. These children were treated in Ruijin Hospital of Shanghai Jiao Tong University from 2007 to 2015. To search for genetic variation in 187 candidate genes which were associated with growth, we constructed a targeted next generation sequencing panel encompassing the coding regions of 187 genes. According to ACMG Guidelines, the sites of variation were determined. Sanger sequencing was used to verify the suspected pathogenic genes variation. The relationship between genotype and clinical phenotype was analyzed. Results Including 5 pathogenic variants, one likely pathogenic variant and one variant of uncertain significance, we identified 7 heterozygous variants of 7 cases in 77 cases of short stature with unknown etiology. A pathogenic variant p.D2407fs of ACAN gene was found in a case with advanced bone age. There were 3 reported pathogenic variants, including p.A72G, p.I282V and p.P491S of PTPN11 gene, which were diagnosed as Noonan syndrome. A ease carrying known pathogenic variant COL2A1 （p.R904C） was diagnosed as Stickler syndrome. We still got one likely pathogenic variant COMP （p.D401N）, which could cause multiple epiphyseal dysplasia. There was a familial short stature of delayed bone age carrying a variant （p.S289Y） of uncertain significance, in which the genotype was in accordance with the clinical phenotype. Conclusion The ACAN gene defection is associated with the idiopathic short stature with advanced bone age. The likely pathogenic variant COMP （p.D4OIN） may cause multiple epiphyseal dysplasia. The newly-found heterozygous varians（p.S289Y） of GHSR gene may result in short stature, which needs further function verification.